Method of tanning hides and skins



Patented Apr. 30, 1935 I I l,999,3

" UNITED STATES PATENT OFFICE METHOD OF TANNING RIDES SKINS Max Hermann, Dresden, Germany, assiznor to Studiengesellschatt der Deutschen Lederlndustrie G. m. b. E, Dresden, Germany No Drawing. Application May 7, 1932, sci-mi Nc.

. 609,988. In Germany May 20,1931

9 Claims. (01. 149-5) It is universally known to use, certain chromic, The following examples will serve to illustrate salts of synthetic tanning substances for tanning the nature 01 the invention, but they are merely or dressing purposes which substances are formed typical cases and can be varied without departure by linking organic compounds and contain free from the nature of the invention. The parts are suite-groups. by weight. I

Now, I have found that aromatic sulfonic acids Example 1 having one nucleus several nuclei and which in Properly prepared and pickled calf skins from themselves possess no tanning properties and are which the hair has been taken om are treated, not formed by linkage of organic molecules, can for the tanning purpose with 2 to 3 per cent be utilized in the form of chronic Salts for solution of p-toluol-sulfonate of chrome, the so- 10 tanning Purposes especially dressing hides called hexaqu'o salt-see G. Jantsoh and K. Mackskins with the result f Pmducmg 'f (Naming enstock, Reports of the Vienna Academy oi Scileathfer 0f Particularly Valuable f i ence, 1929, Division II vol. 138, pag. 337, the Sam chromlc salts may be made m 9 form said solution being controlled and adjusted to adapted to be dissOlVed a Suitable {Elma have a degree of alkalinity as required'or suited the tanning Purpose, but 111 many case? It may be for the tanning process as regards both the initial efemble to lieu thereof Solutlons which and the final condition thereof. The treatment have been a Immediately from any 34mm ofthe skins may be carried outas described either Driate Organic i110! game chmmic salts and in a vat or pit or on a reel or in any other suitable said aromatic sulfonic acids or sulionates which manner knownnin the m solutions thus containing chromic salts of sul- Example 2 f a p a immediately n i t at S to to have an initial alkalinity or basicity of 20 say, within the hides or skins to be tanned, and percent and subsequently of 33 per cent. m in such a case I treat the hides or skins, in suc- The said chrome- -'naphthalino-sulfonate may c ssion first with the one and subsequently with be made by dissolving 40 parts of chromic nitrate the other one of the two substances or com-' in parts of water and mixing the resulting Donents, whereupon I regulate the alkalinity to solution with a solution of parts of p-naphthathe required degree in the usual manner. lino-suli'onic acid dissolved in 150 parts of water. The employment of the described chromic salts Chrome-p-naphthalino-sulfonate will soon be for tanning purposes according to the present precipitated in the mixturein the form of crysinvention involves the advantage of considerably talline scales .of violet colour. Further amounts reducing the possibility or danger of producin of the salt may be recovered from the motherleather of wrinkled or drawn grain as final lye,

.. Example 3 of according the present invention without subjected to a tanning treatment as described in Example 2 with the modification that the alkanecessltty of 'l f hldes sklins to linity of the tanning liquor is controlled to '3 prepara ory rea men wi any par icu ar picka ling agent or, as the case may be any part1 cular amount to 33 per cent from the beginning. hating agent. Example 4 Furthermore, hides and skins treated in the The tanning treatment of t skins is comman herein described for tannins p pos s plished as described in Example 3, but with the and soaked after having been previously dried n tanning liquor rendered basic as -required and the usual way. will rapidly absorb again the divided into several portions which are added amount of water they have lost during the said at intervals in succession, drying operation, and they are just as well adapted to absorb fats and colouring matters with absolute Example 5 5 uniformity. parts of bated calf-skins are fulled in 500 55 parts of a 4 per cent solution of naphthalinosulfonic acid for one hour and subsequently 15 to 20 parts of chrome alum are added to the solution. The alkalinity of the tanning solution is kept first at 20 per cent and later on at 33 per cent.

Example 6 parts of calf skins from which the hair has been removed by like, are freed from adhering lime by treating the same with a solution of naphthaline-sulfonic acid, whereupon the thus prepared skins are subjected to a treatment with chrome-naphthalinosulfonate or with a naphthalino-sulfonic acid and an inorganic chromic salt, for the tanning purpose, the alkalinity of the tanning liquor being kept first at 20 per cent and subsequently at 33 per cent.

Obviously the alkalinity can be controlled or adjusted differently and kept at a higher degree at the beginning or at the termination of the treatment just depending upon the quality of the leather desired to be obtained. In case of using chromic salts of substituted aromatic sulfonic acids devoid of tanning capacity such as alkylized naphthalino-sulfonic acids, the process is to be carried out similarly as described in the foregoing examples.

What I claim is:-

1. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, which comprises preparing the hides and skins in a suitable manner and tanning the same subsequently by means of chromic salts of aromatic sulfonic acids which in themselves possess no tanning properties.

2. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, which comprises preparing the hides and skins in a suitable preparatory treatment and tanning 'the same subsequently by means of chromic salts of aromatic sulfonlc acids having a plurality of nuclei and which possess no tanning properties in themselves.

3. The method the purpose of producing a chrome leather adapted to be soaked again, which comprises pretory treatment and tanning the same subsequently by means of chromic salts of substitution prodnets of aromatic sulfonic acids which in themselves possess no tanning capacity.

4. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, by means of a chrome tanning process, wherein chromic salts of aromatic sulfonic acids which in themselves possess no tanning properties, are formed in the leather from the components thereof, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least one-third of the equi-molecular quantity of the chromic salts.

5. The method of tanning hides and skins for the purpose of producing a chrome leather adaptsteeping in lime or the of tanning hides and skins for ed to be soaked again, which comprises subjecting the hides and skins to a suitable preparatory treatment, treating the prepared hides and skins first with an aromatic sulfonic acid devoid of tanning properties and subsequently with a chromic salts of such an aromatic sulfonic acid, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least one-third of the equi-molecular quantity of the chromic salts.

6. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, which comprises subjecting the hides and skins to a suitable preparatory treatment, treating the prepared hides and skins first with an aromatic sulfonic acid devoid of tanning faculties, and subsequently treating the same with a solution containing an aromatic sulfonic acid devoid of tanning faculties and a chromic salts of any other suitable acid, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least onethird of the equi-molecular quantity of the chromic salts.

7. In the method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, the step of tanning the hides and skins which have not been previously subjected to a pickling treatment, with chromic salts of aromatic sulfonic acids which latter are in themselves devoid of tanning properties, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least one-third of the equi-molecular quantity of the chromic salts.

8. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, which comprises subjecting the hides and skins to a suitable preparatory treatment, treating the prepared hides and skins first with an aromatic sulfonic acid devoid of tanning properties and subsequently with a chromic salt of such an aromatic sulfonic acid, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least one-third of the equi-molecular quantity of the chromic salts, while after the'liming none of the usual methods is used which effect the deliming and the deca i of the hide. paring the hides and skins in a suitable prepara-' y ng 9. The method of tanning hides and skins for the purpose of producing a chrome leather adapted to be soaked again, which comprises subjecting the hides and skins to a suitable preparatory treatment, treating the prepared hides and skins first with an aromatic sulfonic acid devoid of tanning faculties, and subsequently treating the same with a solution containingan aromatic sulfonic acid devoid of tanning faculties and a chromic salt of any other suitable acid, whereupon, at the commencement of tanning the free, aromatic sulfonic acids will contain at least one-third of the equi-molecular quantity of the chromic salts, while after the liming none of the-usual methods is used which effect the deliming and the decaying of the hide.

MAX BERGMANN. 

